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1

The modern approach to manufacturing of carbon-rhenium nanocomposites

Dobrzańska-Danikiewicz A. D., Wolany W.

Journal of Achievements in Materials and Manufacturing Engineering

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2022

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Vol. 115, nr 2

57--63

EN

Purpose: The aim of the paper is to present the high-temperature method of producing MWCNTs-Re nanocomposites, the selection of satisfactory production conditions and the presentation of the results of microscopic and spectroscopic studies of nanocomposites produced by this method. Design/methodology/approach: Two methods of manufacturing carbon-rhenium nanocomposites were tested: ineffective chemical synthesis and high-temperature reduction using H2, which was proven successful and allowed the production of nanocomposites with the expected properties. The received nanocomposites were investigated using Transmission Electron Microscope (TEM), and Scanning Electron Microscope (SEM), as well as were subjected to spectroscopic examination. Findings: The article presents three steps of MWCNTs-Re nanocomposites fabrication using the high-temperature method, functionalization, impregnation and reduction. As part of own work, satisfactory conditions for producing those nanocomposites using a materials science and heuristic analysis were selected. Research limitations/implications: The proposed high-temperature method allows to join rhenium nanoparticles with MWCNTs permanently. It is reasonable to test in the future whether the method is also effective for other carbon nanomaterials and/or nanoparticles of other metals. Practical implications: MWCNTs-Re nanocomposites can be used as sensors of gases that are harmful to the environment. It was also confirmed that the MWCNTs-Re_4 nanocomposite has catalytic properties. Originality/value: The paper presents a modern approach to the manufacturing of MWCNTs-Re nanocomposites, which assumes the use of a high-temperature furnace to heat the material in a hydrogen atmosphere.

2

Heat transfer effects on carbon nanotubes along a moving flat plate subjected to uniform heat flux

Ferdows M., Shamshuddin Md., Reza Motahar, Ara Quadir Raushan

International Journal of Applied Mechanics and Engineering

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2022

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Vol. 27, no. 4

66--81

EN

In the present paper, a theoretical analysis is made to investigate fluid flow and heat energy transformation features of single and multi-walled water functionalized carbon nanotubes (CNTs) with uniform heat inconstancy boundary conditions onward a flat plate. The liquid motion and momentum transfer of carbon nanotubes (CNTs) have been analyzed using a homogeneous flow model. Both single-wall CNTs (SWCNTs) and multi-wall CNTs (MWCNTs) used base fluids, namely, water. The thermophysical characteristics of CNTs regarding the solid volume fraction of CNTs are studied by applying empirical correlations. Similarity transformations have been used to the governing partial differential equations turning them into ordinary differential equations. The outcome of similarity transformations which are nonlinear ordinary differential equations subjected to reconstructed boundary conditions, are subsequently solved numerically using bvp4c. The effects of the governing parameters on the dimensionless velocity, temperature, and skin friction are investigated numerically and graphically. An increase in the volume fraction and the velocity ratio parameter increase the flow, the velocity, and the temperature profile. Regardless of any physical parameter, SWCNTs give better heat transfer than MWCNTs.

3

Effect of multi-walled carbon nanotubes on the damping property of cement mortar and mechanism analysis

Li Yue, Li Hongwen, Jin Caiyun

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 3

289--302

EN

The effect of the type and content of multi-wall carbon nanotubes (MWCNTs) on the damping performance of cement mortar is studied in this paper. The pristine MWCNTs (P-CNT) and the functionalized MWCNTs (F-CNT) grafted with COOH were used in the experiment. The content of MWCNTs was 0.05wt% and 0.1wt% of cement. The flexural/compressive strength and loss factor of CNT-mortar composites were measured. The experimental results show that MWCNTs can significantly enhance the flexural strength and loss factor, and the values increased with the increase of CNTs content. The effect F-CNT was better than P-CNT when the MWCNTs content was the same due to the presence of COOH. The mechanism of MWCNTs reinforced mortar damping performance was analyzed by a variety of micro test techniques. The test results of X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and thermogravimetry showed that MWCNTs did not change the compositions of mortar, but improved the polymerization degree of gel and the degree of hydration of cement. The results of mercury intrusion porosimetry, N2 adsorption and backscattered scanning electron microscopy showed that MWCNTs effectively reduced the porosity and interfacial transition zone thickness of mortar. Transmission electron microscope results showed that the energy dissipation capacity of mortar is increased due to the bridging effect of MWCNTs.

4

Electrical and thermal characteristics of MWCNTs modified carbon fiber/epoxy composite films

Kareem Aseel A., Rasheed Hussein K.

Materials Science Poland

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2019

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Vol. 37, No. 4

622--627

EN

To enhance interfacial bonding between carbon fibers and epoxy matrix, the carbon fibers have been modified with multiwall carbon nanotubes (MWCNTs) using the dip- coating technique. FT-IR spectrum of the MWCNTs shows a peak at 1640 cm−1 corresponding to the stretching mode of the C=C double bond which forms the framework of the carbon nanotube sidewall. The broad peak at 3430 cm−1 is due to O–H stretching vibration of hydroxyl groups and the peak at 1712 cm−1 corresponds to the carboxylic (C=O) group attached to the carbon fiber. The peaks at 2927 cm−1 and 2862 cm−1 are assigned to C–H stretching vibration of epoxy produced at the defect sites of acid-oxidized carbon fiber surface. SEM image shows a better interface bonding between the fiber and the matrix of modified composites (MWCNTs-CF/Ep) than those of unmodified composite. The loss factor curve of CF-MWCNTs/Ep composites is the narrowest compared with neat epoxy and CF/Ep composites which evinces that the length distribution range of molecular chain segments in the matrix is the narrowest. From the dependence of the AC conductivity on temperature, we can see that σAC increases when temperature increases. The increase in electrical conductivity of the composites may be a result of the increased chain ordering due to annealing effect. The use of MWCNTs to modify the surface of carbon fiber resulted in a large amount of junctions among MWCNT causing an increase in the electrical and thermal conductivity by forming conducting paths in the matrix. The MWCNTs-CF/Ep composite shows better thermal stability than unmodified composites. The strong interaction between CF and MWCNTs can retard diffusion of small molecules from the resin matrix at high temperature and hence, result in the improved thermal stability of the modified CF/Ep composite.

5

Determination of five pyrethroid pesticides residue in liquid milk by gas chromatography using multi-walled carbon nanotubes as dispersion solid phase extraction sorbent

Gao Y. L., Sun P.

Acta Chromatographica

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2018

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Vol. 30, no. 2

141--146

EN

A novel multi-walled carbon nanotubes (MWCNTs) dispersive solid phase extraction (d-SPE) method which combined with gas chromatography (GC) coupled with electron capture detector (ECD) was developed for the determination of five pyrethroid pesticides in liquid milk for the first time. The effect of d-SPE conditions on the kinds of sorbent, MWCNTs and magnesium sulfate anhydro mass ratio, and extraction condition were researched, and then, the suitable method was found. Under the optimal conditions, the linear range was from 20 to 500 μg kg−1. The recoveries were from 81.8% to 112.1%, with the corresponding relative standard deviations (RSDs) less than 6%, correlation coefficients from 0.9978 to 0.9990, and limits of detection and quantification from 2.62 to 4.86 μg kg−1 and 8.73 to 16.2 μg kg−1. The proposed method is simple, fast, safe, and has high recovery and sensitivity applicable to analyze pyrethroid pesticides in liquid milk sample.

6

Preparation and electrical properties of polyimide/carbon nanotubes composites

Kareem A. A.

Materials Science Poland

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2017

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Vol. 35, No. 4

755--759

EN

Polyimide/MWCNTs nanocomposites have been fabricated by solution mixing process. In the present study, we have investigated electrical conductivity and dielectric properties of PI/MWCNT nanocomposites in frequency range of 1 kHz to 100 kHz at different MWCNTs concentrations from 0 wt.% to 15 wt.%. It has been observed that the electrical conductivity and dielectric constants are enhanced significantly by several orders of magnitude up to 15 wt.% of MWCNTs content. The electrical conductivity increases as the frequency is increased, which can be attributed to high dislocation density near the interface. The rapid increase in the dielectric constant at a high MWCNTs content can be explained by the formation of a percolative path of the conducting network through the sample for a concentration corresponding to the percolation threshold. The high dielectric constant at a low frequency (1 kHz) is thought to originate from the space charge polarization mechanism. I-V characteristics of these devices indicate a significant increase in current with an increase in multi-walled carbon nanotube concentration in the composites. The SEM images show improved dispersion of MWCNTs in the PI matrix; this is due to the strong interfacial interactions.

7

Magneto-thermo-mechanical creep behavior of nano-composite rotating cylinder made of polypropylene reinforced by MWCNTs

Loghman A., Shayestemoghadam H.

Journal of Theoretical and Applied Mechanics

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2016

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Vol. 54 nr 1

239--249

EN

History of strains, stresses and displacements of a rotating cylinder made of polypropylene reinforced by multi-walled carbon nanotubes (MWCNTs) subjected to magneto-thermo- -mechanical loading is investigated using Burgers viscoelastic creep model. By making use of equations of equilibrium, stress-strain and strain-displacement, a constitutive differential equation containing creep strains is obtained which is solved semi analytically. It has been found that radial displacement, tangential strain and absolute values of radial strain are increasing with time at a decreasing rate so that they finally approach the steady state condition. Effective stresses are decreasing at the inner and increasing at the outer surface of the cylinder.

8

Manufacturing and structure of nanocomposites consisting of MWCNTs decorated respectively with Rh, Re and Pt nanocristals

Dobrzańska-Danikiewicz A. D., Łukowiec D., Wolany W., Cichocki D.

Journal of Achievements in Materials and Manufacturing Engineering

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2015

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Vol. 72, nr 1

39--44

EN

Purpose: The primary aim of the paper is to compare fabrication methods and present newly fabricated nanocomposites whose structural components are multi-walled carbon nanotubes (MWCNTs) and respectively Rh, Re and Pt nanocrystals. Design/methodology/approach: The newly fabricated nanocomposites underwent Transmission Electron Microscopy (TEM) examinations in the bright to show their structure. Spectroscopy examinations were carried out, as well, to determine chemical composition of the material. Findings: It was found based on a comparative analysis of the structure of selected nanocomposites that functionalisation methods and a reduction method of precursors of selected noble elements have a significant effect on the structure and morphology of the compared carbon nanocomposites. Research limitations/implications: Nanocomposites consisting of carbon nanotubes decorated with metal nanoparticles possess special electrical properties and a developed specific area, which makes them particularly suitable as active elements of industrial gas sensors. The materials can also be used as biosensors and catalysts in the future. Originality/value: The paper presents the results of investigations relating to the synthesis of nanocomposites consisting of multiwalled carbon nanotubes and respectively Rh, Re and Pt nanocrystals and their structure and chemical composition.

9

Reductive Debenzylation of Hexabenzylhexaazaisowurtzitane using Multi-walled Carbon Nanotube-supported Palladium Catalysts: an Optimization Approach

Bayat Y., Malmir S., Hajighasemali F., Dehghani H.

Central European Journal of Energetic Materials

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2015

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Vol. 12, no. 3

439--458

EN

This study focuses on the optimization of parameters affecting the reductive debenzylation of hexabenzylhexaazaisowurtzitane using multiwalled carbon nanotube-supported palladium catalysts. Initially the influence of functionalized carbon nanotubes, including OH and COOH groups, were compared with basic multi-walled carbon nanotubes, and their impact on the reaction yield was evaluated. Among these catalyst supports, hydroxylated multi-walled carbon nanotubes showed superior efficiency for producing tetraacetyldibenzylhexaazaisowurtzitane from hexabenzylhexaazaisowurtzitane. The effect of catalyst preparation factors on the reaction yield were screened by using a 25-2 fractional factorial design. Parameters, including percent palladium, adsorption time, pH and adsorption temperature, were optimized by applying a central composite design. The optimum values of these factors were: 12.97% Pd, adsorption time 1.81 h, pH 9.61 and adsorption temperature 42.78 °C. A value of 76% was obtained for the reaction yield under optimum conditions.

10

Physiochemical and biological evaluation of thin CNTs layers

Benko A., Przekora A., Nocuń M., Wesełucha-Birczyńska A., Ginalska G., Błażewicz M.

Engineering of Biomaterials

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2014

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Vol. 17, no. 128-129

93--94

EN

Carbon nanotubes are nanometric-sized materiale which possess a set of interesting features that favor their applications in various fields of materials engineering, including biomedical applications. However, their usage as implants or in nanomedicine raises many questions, regarding their potential cytotoxicity, relative to their length, diameter, structure and functional groups, present on their outer walls. The given study presents a physiochemical and biological in vitro (in accordance with EN-ISO 10993-5) evaluation of thin carbon nanotubes films, deposited on the surface of titanium, by means of the EPD process. Experiments were carried out on commercially available, pre-functionalized with OH groups, multi-walled carbon nanotubes. The obtained material is proven to be biocompatible, with no cytotoxic effect on the human fetal osteoblast cell line. During the study, selectivity of the EPD process was proven - performed experiments revealed that the process favors deposition of CNTs with chosen set of features from the stock solution. Presented results point out that the EPD process can be successfully applied as a method for fractioning the CNTs, aimed to fabricate non-toxic layers that might be considered for various biomedical applications.

11

Photodegradation of organic dyes over nickel distributed CNT/TiO2 composite synthesized by a simple sol-gel method

Chen M. L., Oh W. C.

Materials Science Poland

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2011

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Vol. 29, No. 2

112--120

EN

In this study, the multi-walled carbon nanotubes were oxidized by m-chlorperbenzoic acid followed by the reaction with titanium n-butoxide and nickel nitrate to prepare Ni distributed CNT/TiO2 composite by a simple sol-gel method. The functional groups formed on the surface of MWCNTs were analyzed by Fourier transform infrared spectroscopy. The prepared Ni distributed CNT/TiO2 composite was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray analysis. The photodegradation of methylene blue, methylene orange and rhodamine B solution under UV irradiation was employed to test the photocatalytic activity of the Ni distributed CNT/TiO2 composite. According to the results, Ni distributed CNT/TiO2 composite showed very excellent photocatalytic activity to decompose MB, MO and Rh.B solutions, due to the electron absorption effect of MWCNTs and electron trapping effect of nickel.